After years of ambiguity surrounding early issues with the Scarborough subway extension tunnel, newly released documents confirm it took several months to fix the tunnel-boring machine as it sat stationary near Highway 401.The details were contained in a freedom of information request filed and released by the Ontario NDP on Wednesday. The internal documents were from late 2024 and early 2025. Much of the 493-page response from the Ontario government was redacted, citing reasons such as non-responsiveness, “settlement privilege,” economic interests and advice to the government.As the documents noted, tunnelling by Strabag began in January 2023 (which was “slightly behind their original schedule) and it was supposed to be substantially completed by October 2024. Original projections had the tunnel-boring machine (TBM) moving 10 to 15 metres a day. The construction firm was awarded a $757-million contract in 2021 to build the 7.8-kilometre tunnel.The documents said Strabag first encountered issues about 50 metres into tunnelling. Throughout 2023 and 2024, one timeline said there were “continued subsidence (process of land sinking) issues.” In spring 2024, pre-planned maintenance on the tunnel-boring machine was performed. In June of that year, it dug under Highway 401. Related:Scarborough subway extension tunnelling stalled near Highway 401 for monthsCrews had to conduct partial lane closures on Highway 401 for a “compensation grouting campaign” to address areas on the shoulders where there was “minor surface settlement.”Days later, the machine was parked just south of the highway between two eastbound on-ramps east of McCowan Road. “Strabag has stopped the TBM due to concern over elevated cutterhead torque and thrust forces experienced during the last [three to four] advances. They have determined that a series of repairs and improvements are required to the TBM and that such repairs must be performed in atmospheric conditions,” one of the documents from August 2024 said.It said a “safe-haven concrete block” made up of 83 concrete piles was needed for crews to access the massive machine. It said the whole process would take eight months.In a slide about “communications considerations,” Metrolinx and Infrastructure Ontario officials said a “reactive” communications plan was in development. It said the machine’s “delay from Strabag’s original schedule has not attracted significant public attention to date,” adding that the original plan for a website to track the machine and corresponding social media posts “was never launched.”Related:Soil conditions ‘hampering’ Scarborough subway extension tunnelling, Metrolinx CEO says“At this point, it is recommended that we communicate about the cumulative impacts of the various interventions that have been required,” a separate communications briefing memo said. “Residents and stakeholders with an interest in the Scarborough Subway Extension project are closely following the work as it progresses, and need tobe updated and kept informed of this planned work, which will affect the original expected schedule for tunnelling. “The project’s community engagement and communications teams are regularly questioned about the progress and current location of the TBM, and many are pointing out that tunnelling seems to be slow.”There wasn’t a detailed update provided in the latter part of 2024. Also, there was little to no detailed information provided on the project’s social media accounts — something that occasionally sparked questions from residents.As CityNews previously reported, it wasn’t until a November board meeting that former Metrolinx president and CEO Phil Verster said soil conditions were “hampering” tunnel construction.Related:Scarborough subway extension tunnelling quietly resumes as budget forecast tops $10BTwo task forces were formed to address commercial and technical issues affecting the project and to create a new schedule for completion. The documents noted Strabag was increasing its staffing and hours of operation. Metrolinx nor the Ontario government have held a public information session to address the findings.However, an update to the Metrolinx board in June 2025 quietly revealed the TBM was on the move again at a rate of around 12 metres a day. At that point, it was closing in on the future Scarborough Centre station. Meanwhile, work on building the extension is continuing across the route. Construction on the stations and other above-ground infrastructure is actively underway.The total budget for building and operating the Scarborough subway extension is just over $10 billion. It’s expected to open in 2030.